U.S. patent application number 11/564224 was filed with the patent office on 2007-05-31 for vacuum belt conveying device for guiding a moving web.
This patent application is currently assigned to Andritz Kusters GmbH & Co. KG. Invention is credited to Andreas Pesch, Bernhard Schmitz.
Application Number | 20070119895 11/564224 |
Document ID | / |
Family ID | 37807982 |
Filed Date | 2007-05-31 |
United States Patent
Application |
20070119895 |
Kind Code |
A1 |
Pesch; Andreas ; et
al. |
May 31, 2007 |
VACUUM BELT CONVEYING DEVICE FOR GUIDING A MOVING WEB
Abstract
Vacuum belt conveying device for guiding a moving web, in
particular a web threading strip of a paper or board web, having an
air-permeable transport belt guided endlessly in a loop with an
upper run and a lower run, and a device arranged within the loop
for applying a vacuum to the inner side of one of the runs of the
transport belt in order to hold the web firmly on the transport
belt, in which the device for applying a vacuum is formed by means
of at least one long-gap ejector, which in each case has an air jet
injector having a large number of air outlet nozzles along the
inlet side of the long gap and, on the inlet side, is positioned at
a distance under the inner side of the run which is provided to
hold the web firmly.
Inventors: |
Pesch; Andreas; (Krefeld,
DE) ; Schmitz; Bernhard; (Willich, DE) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
Andritz Kusters GmbH & Co.
KG
Krefeld
DE
|
Family ID: |
37807982 |
Appl. No.: |
11/564224 |
Filed: |
November 28, 2006 |
Current U.S.
Class: |
226/95 |
Current CPC
Class: |
D21G 9/0063 20130101;
B65H 20/10 20130101; B65H 2301/522 20130101 |
Class at
Publication: |
226/095 |
International
Class: |
B65H 20/10 20060101
B65H020/10 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 30, 2005 |
DE |
102005057426.2 |
Claims
1. Vacuum belt conveying device for guiding a moving web, in
particular a web threading strip of a paper or board web, having an
air-permeable transport belt guided endlessly in a loop with an
upper run and a lower run, and a device arranged within the loop
for applying a vacuum to the inner side of one of the runs of the
transport belt in order to hold the web firmly on the transport
belt, wherein the device for applying a vacuum is formed by means
of at least one long-gap ejector, which in each case has an air jet
injector having a large number of air outlet nozzles along the
inlet side of the long gap and, on the inlet side, is positioned at
a distance under the inner side of the run which is provided to
hold the web firmly.
2. Vacuum belt conveying device according to claim 1, wherein the
at least one long-gap ejector produces a flow in a gap space via a
nozzle stock arranged in the gap longitudinal direction.
3. Vacuum belt conveying device according to claim 2, wherein the
gap space is formed with a narrowed cross section.
4. Vacuum belt conveying device according to one of claims 1 to 3,
wherein within the loop there is arranged a dividing wall, which
divides a suction chamber, in which the inlet side of the at least
one long-gap ejector is arranged, from an outward flow chamber, in
which an outlet side of the at least one long-gap ejector is
arranged.
5. Vacuum belt conveying device according to claim 4, wherein the
suction chamber and outward flow chamber have transverse walls
between adjacent long-gap ejectors.
6. Vacuum belt conveying device according to claim 4 or 5, wherein
the suction chamber can be connected to the outward flow chamber
via at least one restrictor in order to limit a vacuum.
7. Vacuum belt conveying device according to claim 6, wherein the
at least one restrictor is arranged in a dividing wall between
suction chamber and outward flow chamber in order to control a flow
rate.
8. Vacuum belt conveying device according to one of claims 1 to 7,
wherein the at least one long-gap ejector is arranged to operate at
right angles to the transport belt.
9. Vacuum belt conveying device according to one of claims 1 to 8,
wherein the at least one long-gap ejector is arranged to operate at
an angle to the transport belt.
10. Vacuum belt conveying device according to one of claims 1 to 9,
wherein the at least one long-gap ejector in each case has a gap
space which has an outlet portion with a widened cross section.
11. Vacuum belt conveying device according to one of claims 1 to
10, wherein the at least one long-gap ejector in each case has a
gap space with a selectable flow path length.
12. Vacuum belt conveying device according to claim 9, wherein the
flow path length of the gap space having a narrowed cross section
is 50 to 80% of the total flow path length of the gap space.
13. Vacuum belt conveying device according to one of claims 1 to
12, wherein the air jet injector is arranged in a converging inlet
region of a long-gap ejector.
14. Vacuum belt conveying device according to one of claims 1 to
13, wherein the at least one long-gap ejector is arranged
transversely with respect to the running direction of the transport
belt.
15. Vacuum belt conveying device according to one of claims 1 to
14, wherein the at least one long-gap ejector is arranged obliquely
with respect to the running direction of the transport belt.
16. Vacuum belt conveying device according to one of claims 1 to
14, wherein a plurality of long-gap ejectors are arranged adjacent
to one another in the running direction of the transport belt.
17. Vacuum belt conveying device according to claim 16, wherein,
depending on the running length of the transport belt, at least two
long-gap ejectors are arranged at a distance from each other in the
running direction of the transport belt.
18. Vacuum belt conveying device according to claim 16 or 17,
wherein the long-gap ejectors are arranged with the gap
longitudinal direction in the running direction of the transport
belt, forming at least one vacuum strip.
19. Vacuum belt conveying device according to one of claims 1 to
18, wherein the at least one long-gap ejector has an inlet region
with rounded short side edges.
20. Vacuum belt conveying device according to one of claims 1 to
19, wherein the at least one air jet injector can be fed via feed
lines arranged laterally on the transport belt.
21. Vacuum belt conveying device according to one of claims 1 to
20, wherein an outward flow chamber can be encapsulated for
controllable dissipation of the air flowing out.
22. Vacuum belt conveying device according to one of claims 1 to
21, wherein air can be supplied to the at least one long-gap
ejector via a feed line, and the pressure of the air can be
adjusted.
23. Vacuum belt conveying device according to claim 22, wherein a
plurality of long-gap ejectors are arranged adjacent to one
another, and air can be supplied to the feed lines at a
respectively adjustable pressure.
Description
[0001] The invention relates to a vacuum belt conveying device for
guiding a moving web, in particular a web threading strip of a
paper or board web.
[0002] Vacuum belt conveying devices for guiding a moving web are
used in different industrial installations in order to be able to
hold a web securely on a transport path. This applies in particular
to paper and board machines, where the web is transferred from one
machine section to another machine section, for example from the
wet section to the drying section or from the drying section to the
finishing section.
[0003] DE 100 09 188 A1 discloses the use of vacuum belt conveying
devices in paper or board machines in order to make it easier to
thread the paper or board web into a machine for the production or
finishing or further processing of such a web. During the starting
of a paper machine or when restarting after a web break, a narrow
strip or threading strip is severed from the moving web. This strip
is transferred with the aid of the vacuum belt conveying device,
for example from the end of one machine section to the input region
of a following machine section. For this purpose, the conveying
device comprises an air-permeable, endless conveyor belt, which
runs over two rollers and over a suction box or vacuum box.
Consequently, the threading strip is attracted to the conveyor belt
by suction and transported. In order to produce a vacuum or a
negative pressure within the suction box, a vacuum blower is
provided. The vacuum blower comprises an impeller which has an
outlet duct. The impeller is driven by a suitable motor. The
suction box has one or more suction openings, via which the vacuum
blower produces negative pressure in the interior of the suction
box. The complicated and large-format construction is
disadvantageous, additionally requires maintenance and is expensive
to produce and to operate. Sealing the suction box is additionally
difficult.
[0004] DE 35 24 006 A1 discloses a device for the transport and for
the guidance of the web end threading strip into a paper machine,
which comprises a transport belt arranged around two or more
deflection rolls, which is air-permeable and within whose loop
devices are fitted with which a vacuum effect is achieved on the
one run of the transport belt with which the end threading strip is
transported, by which means the end threading strip is attached to
the aforementioned run and held firmly thereon. The vacuum is
produced by air blowing devices which are fitted within the loop
and comprise guide plates, which extend substantially parallel to
the plane of the transport belt and on which a dynamic vacuum
effect can be produced by air blowing means, with which the end
threading strip is attached to the transport belt. The disadvantage
is that, in order to blow on the guide plates, a rather large
quantity of air is needed, which has to be led away and leads to
undesired blown streams in the region around the device.
[0005] DE 299 24 658 U1 discloses a device for conveying and
guiding a threading strip of a web in a paper machine of the
aforementioned type, in which the device for producing a vacuum
effect has curved air flow guiding surfaces along the transport
belt which, in conjunction with foil heads, produce a vacuum. By
adjusting the angle of the air flow guiding surfaces, the level of
the vacuum can be regulated. Positive pressure regions which arise
upstream of the foil heads are disadvantageous.
[0006] DE 200 01 082 U1 discloses a blower box. The walls of the
blower box are double-layered. Between the layers of each wall a
region is thus produced in which a pressure level that is lower
than the pressure level of the surrounding air can be established
in a targeted manner. Because of this, the air can flow out of the
surroundings into the regions between the layers, so that the
desired pressure level in the space is no longer affected
detrimentally to a relevant extent. Consequently, an edge seal is
generally created for spaces in which a lower pressure is to
prevail than in the surroundings. Provision is made here for air
injectors to be incorporated in the regions between the layers of
the walls, the outlet openings of the said air injectors facing
away from the gaps at the edge.
[0007] The object of the invention is, therefore, to provide a
vacuum belt conveying device for guiding a moving web which is
constructionally simple and takes up little space.
[0008] This object is achieved by the features of Claim 1.
[0009] In this way, a vacuum belt conveying device for guiding a
moving web, in particular a web threading strip, is provided, whose
device for applying a vacuum, in addition to a low overall height,
has a form matched to the intended use, namely a rectangular form.
In this case, the suction output is high and can be adjusted in the
longitudinal and transverse direction. Drops in pressure between
individual suction centres are minimized, so that a substantially
uniform vacuum can be set over the width and/or the length of the
transport belt in order to hold a web.
[0010] A nozzle row arrangement of the at least one long-gap
ejector preferably extends transversely with respect to the belt
running direction and produces an air stream at right angles to the
belt. The air stream can than also simply be led away downwards,
hindrances arising from undesired air streams in the region of the
device being minimized.
[0011] A gap space of the at least one long-gap ejector preferably
has a portion having a narrow cross section in order to achieve a
high efficiency. If a lower efficiency is adequate, the gap space
can also be formed without a cross-sectional narrowing.
[0012] The at least one long-gap ejector can also operate in
conjunction with a suction chamber, for which purpose a dividing
wall can be provided within the loop. The dividing wall is
preferably arranged in the longitudinal direction of the transport
belt and at a distance underneath the run which is provided to hold
the web firmly. As a result, a suction chamber above the dividing
wall is separated from an outward flow chamber below the dividing
wall. The outward flow chamber is formed in a region above the
other, return run and can be open to the outside or closed. If a
plurality of long gap ejectors are arranged one after another in
the longitudinal direction, it is also possible for transverse
dividing walls to be provided, which subdivide the suction chamber
and, if appropriate, the outward flow chamber into a plurality of
chambers arranged one after another. In this way, selectable vacuum
profiles can be set along the transport belt.
[0013] If a dividing wall is provided, a passage which is provided
with an adjustable restrictor can be provided therein. Via the
restrictor, a flow rate can be determined and therefore a maximum
vacuum level can be set. The arrangement of the at least one
long-gap ejector can be carried out such that it operates at right
angles to the transport belt or at an angle to the transport
belt.
[0014] The at least one long-gap ejector can have a gap space which
has a cross-sectional narrowing on the outward flow side. As a
result, the air flowing out can experience better distribution.
[0015] The at least one long-gap ejector can have a gap space whose
flow path length can be selected. Consequently, the gap space can
be used not only to take air in to produce a vacuum but, at the
same time, can also be used to guide the air away in a specific
manner from the region of the application of vacuum. In order to
improve the vacuum attachment further, the air jet injector can be
arranged in a convergent inlet region of the at least one long-gap
ejector.
[0016] The alignment of the inlet region of the long-gap ejector or
ejectors in relation to the running direction of the transport belt
can be selected. The inlet region can be arranged transversely or
obliquely with respect to the running direction or in the running
direction; in the case of a plurality of long-gap ejectors, these
can be arranged at a distance or immediately adjacent to one
another in order to form selectable vacuum areas. In particular
when a plurality of long-gap ejectors in the running direction form
a vacuum strip in the running direction, only one row of long-gap
ejectors, for example one central strip, can be provided or a
plurality of rows of long-gap ejectors can be arranged in parallel
with and at a distance from one another, for example two edge
strips.
[0017] Further refinements of the invention can be gathered from
the following description and the subclaims.
[0018] The invention will be explained in more detail below by
using the exemplary embodiments illustrated in the appended
drawings, in which:
[0019] FIG. 1 shows, schematically, a plan view of a vacuum belt
conveying device,
[0020] FIG. 2 shows a section A-A according to FIG. 1 for a vacuum
belt conveying device according to a first exemplary
embodiment,
[0021] FIG. 3 shows, schematically, a plan view of a long-gap
ejector of the vacuum belt conveying device according to FIG.
2,
[0022] FIG. 4a shows a section B-B of the long-gap ejector
according to FIG. 3,
[0023] FIG. 4b shows the region X from FIG. 4a enlarged,
[0024] FIG. 5 shows a perspective view of the long-gap ejector
according to FIG. 3,
[0025] FIG. 6 shows a section A-A according to FIG. 1 for a vacuum
belt conveying device according to a second exemplary
embodiment,
[0026] FIG. 7 shows a section A-A according to FIG. 1 for a vacuum
belt conveying device according to a third exemplary
embodiment,
[0027] FIG. 8 shows a section A-A according to FIG. 1 for a vacuum
belt conveying device according to a fourth exemplary
embodiment,
[0028] FIG. 9 shows, schematically, a plan view of a vacuum belt
conveying device according to a fifth exemplary embodiment,
[0029] FIG. 10 shows, schematically, a plan view of a vacuum belt
conveying device according to a sixth exemplary embodiment,
[0030] FIG. 11 shows, schematically, a plan view of a vacuum belt
conveying device according to a seventh exemplary embodiment,
[0031] FIGS. 12a and 12b each show a section A-A according to FIG.
1 for a vacuum belt conveying device according to an eighth and a
ninth exemplary embodiment.
[0032] FIG. 1 shows a vacuum belt conveying device 1 for guiding a
moving web 2, in particular a web threading strip of a paper or
board web. The vacuum belt conveying device 1 comprises deflection
rolls 3 and 4, between which a transport belt 5 is arranged. The
transport belt 5 is guided endlessly in a loop 8 having an upper
run 6 and a lower run 7, as shown, for example, in FIG. 1. The
transport belt 5 is air-permeable and, to this end, comprises a
cloth with adequate permeability or a material web with a
perforated structure.
[0033] Arranged within the loop 8 is a device 9 for applying a
vacuum to the inner side of one of the runs of the transport belt,
the upper run 6 here, in order to hold the web 2 firmly on the
transport belt 5. The device 9 for applying a vacuum is formed by
means of at least one long-gap ejector 10, 11, which in each case
has an air jet injector 12, 13 having a large number of air outlet
nozzles 14 along the inlet side 15, 16 of the long gap 17, 18 and,
on the inlet side, is positioned at a distance underneath the inner
side of the run 6 provided for holding the web firmly. Via air feed
lines 21, 22 connected laterally to the transport belt 5, the air
jet injector 12, 13 of the at least one long-gap ejector 10, 11 is
fed from an air source, not illustrated, in order to be able to
inject air into the associated long gap 17, 18. The air fed in
flows at high velocity through the air outlet nozzles 14, by which
means air which is located in the surroundings of the top of the at
least one long- gap ejector 10, 11 is taken in on the inlet side
15. In this way, a vacuum can be applied to the inner side of the
run 6 via one or more air nozzles being fitted underneath the belt
5. The pressure of the air supplied is adjustable, which means that
an influence can be exerted on the suction performance. If a
plurality of long-gap ejectors 10, 11 are arranged one after
another in the running direction, these can be given the same or a
different air supply in order as a result to configure individually
adjustable suction output profiles in the transport direction
T.
[0034] The construction of the at least one long-gap ejector 10, 11
is illustrated in detail in FIGS. 3 to 5 for one long-gap ejector
10. The following explanations apply in the corresponding way to
all the other long-gap ejectors. Accordingly, the long-gap ejector
10 has a substantially rectangular form and has an air jet injector
12. The air jet injector 12 is formed by a nozzle stock 19, which
is arranged in the gap longitudinal direction and produces an air
stream in the gap space 20 of the long gap 17. The nozzle stock 19
is preferably arranged to be countersunk with respect to the inlet
side 15, which means that the air taken in on the inlet side is
deflected into the gap space 20. The air jet injector 12 is
preferably seated in a convergent inlet region 23 of the long-gap
ejector 10, the short side edges 24, 25 of the long gap 17
preferably being rounded.
[0035] The long gap 17 of the long-gap ejector 10 can delimit the
gap space 20 with parallel surfaces from the inlet side 15 up to an
outlet side 26, that is to say extend without a narrowed cross
section (cf. FIGS. 12a, 12b). For a high efficiency, the gap space
20 should preferably be formed with a narrowed cross section. The
inlet region 23 with convergent side surfaces then extends until
under the air jet injector 12. The narrowing in the cross section
of the long gap 17 promotes the formation of a closed flow and
therefore advantageous sealing of the air jet injector 12. The
suction performance of a long-gap ejector 10, 11 on the inlet side
15 can be controlled via the air stream fed in and by the shape of
the long gap 17 between inlet side 15 and outlet side 26. The
length of the long gap 17 in the flow direction can be selected and
opens up advantageous dissipation of the air.
[0036] On the outlet side 26, the long gap 17 is preferably formed
with a widened cross-sectional portion 40, which improves the
outward flow behaviour of the long-gap ejector 10 in relation to a
wide air outlet distribution. Even in the case of a narrowed cross
section of the long gap on the inlet and/or outlet side, the long
gap 17 preferably has a portion with parallel side surfaces, which
can make up about 50 to 80% of the total length of the long gap 17
in the flow direction between inlet side 15 and outlet side 26. To
this extent, the long gap 17 forms a guide duct for the air stream
with a selectable flow path length.
[0037] In the first exemplary embodiment of a vacuum belt conveying
device, illustrated in FIG. 2, the device 9 for applying the vacuum
comprises two long-gap ejectors 10, 11, which are arranged one
after the other at a distance in the transport direction T. The
number of long-gap ejectors 10, 11 arranged beside one another can
be selected. The distance from the inner side of the run 6 can
likewise be selected and depends on the suction performance. A
minimum distance ensures that although the suction region is local
it is sufficiently flat. The extent of the long gap 17 in the gap
longitudinal direction can be selected as a function of a width of
the transport belt 5 in order that attraction by suction takes
place over the entire width of the transport belt 5. In the
transport direction T, the long-gap ejector or ejectors 10, 11 can
be arranged at selectable points, that is to say can be positioned
where a suction attraction characteristic is desired. The
respective air jet injector 12 having the associated nozzle stock
19 preferably extends transversely with respect to the belt running
direction T for this purpose and produces an air stream at right
angles to the belt 5. Here, the long-gap ejectors 10, 11 are
arranged to operate at right angles to the transport belt 5.
[0038] For positioning the at least one long-gap ejector 10, 11, a
holder 27 is provided which holds the long-gap ejectors 10, 11 in a
fixed location in the loop 8. Furthermore, the long-gap ejectors
10,11 can be arranged in a self-supporting manner in the loop 8.
The holder 27 can be formed by a frame belonging to the device 1,
in which the deflection rolls 3, 4 are also mounted.
[0039] The transport belt 5 is moved in the transport direction T
by at least one driven deflection roll 3, 4. According to FIG. 2, a
drive motor 28 is provided for the deflection roll 3 for this
purpose. In order to support the transport belt 5 on the loop
between the deflection rolls 3, 4, supporting grids, not
illustrated, can be provided.
[0040] According to a second exemplary embodiment of the vacuum
belt conveying device, illustrated in FIG. 6, a dividing wall 29 is
arranged within the loop 8. The dividing wall 29 divides a suction
chamber 33, 34, in which the inlet side 15 of the at least one
long-gap ejector 10, 11 with its respective inlet is arranged, from
an outward flow chamber 35, 36, in which the outlet side 26 of the
at least one long-gap ejector 10, 11 with its respective outlet is
arranged. For this purpose, the dividing wall 29 preferably extends
substantially parallel to the transport belt 5. The suction chamber
33, 34 preferably forms an upper chamber and the outward flow
chamber 35, 36 forms a lower chamber, which is delimited at the
sides with respect to the deflection rolls 3, 4 by covering plates
31, 32.
[0041] The suction chamber 33, 34 is delimited at the top by the
run 6 of the air-permeable transport belt 5. Alternatively, the
delimitation at the top can be provided by a perforated plate, on
which the run 6 runs in a guided manner. The distribution and also
the opening widths of the holes permit an influence to be exerted
on the vacuum characteristics on the inner side of the run 6. The
outward flow chamber 35, 36 is delimited at the bottom by the
return run 7. If a plurality of long-gap ejectors 10, 11 are
arranged, for example two, as illustrated in FIG. 6, the long-gap
ejectors 10, 11 are assigned a suction chamber 33, 34 and an
outward flow chamber 35, 36. By means of a transverse dividing wall
30, the subdivision of the suction chambers 33, 34 and of the
outward flow chambers 35, 36 is possible. The at least one long-gap
ejector 10, 11 takes air in from the respective suction chamber 33,
34, by which means a suction area corresponding to the suction
chamber 33, 34 is applied to the inner side of the run 6. The
distance of the inlet side 15 of the at least one long-gap ejector
10, 11 from the inner side of the run 6 can be chosen to be greater
than in the case of the self-supporting long-gap ejectors 10, 11
according to FIG. 2. In order to take the air in from the
respective suction chamber 33, 34 as uniformly as possible, the
inlet side 15 is preferably positioned in a central region of the
suction chamber 33, 34. Otherwise, the above explanations relating
to the first exemplary embodiment apply in a corresponding way
here.
[0042] According to a third exemplary embodiment of the vacuum belt
conveying device 1, illustrated in FIG. 7, an adjustable restrictor
37, 38 is arranged in the dividing wall 29. Via the restrictors 37,
38, a flow rate between a suction chamber 33, 34 and an outward
flow chamber 35, 36 can be determined, and therefore a maximum
vacuum level can be set in a suction chamber 33, 34. A maximum
vacuum in the suction chamber 33, 34 can be defined via such a
bypass between suction chamber 33, 34 and outward flow chamber 35,
36. Beginning at a specific vacuum value, no further vacuum is
built up, since the bypass flow via the restrictors 37, 38 then
corresponds to the output suction flow. A specific pressure
difference is set. The vacuum level is additionally adjustable. The
risk that, in particular, relatively wet paper or board webs on the
transport belt 5 will be damaged by excessively intense suction
attraction therefore does not exist. Each suction chamber 33, 34
with associated outward flow chamber 35, 36 is preferably assigned
a restrictor 37, 38. In addition, the drive power of the motor 28
can be kept low by limiting the vacuum level. Otherwise, the above
explanations relating to the first and second exemplary embodiments
apply in a corresponding way here.
[0043] The fourth embodiment of the vacuum belt conveying device,
illustrated in FIG. 8, differs from the third embodiment,
illustrated in FIG. 7, in that the at least one long-gap ejector
10, 11 is not arranged to operate at right angles to the transport
belt 5 but is arranged to operate at an angle to the transport
belt. The long-gap ejectors 10, 11 are inclined or tilted with
respect to the transport plane of the transport belt 5. The suction
attraction can be built up so as to lead or lag the outward flow
with respect to the transport direction T. Otherwise, the above
explanations relating to the other exemplary embodiments apply in a
corresponding way here.
[0044] The exemplary embodiments of the vacuum belt conveying
device 1 illustrated in FIGS. 9 to 11 relate to different
arrangements of the at least two long-gap ejectors 10, 11 in
relation to the running direction T. In the fifth exemplary
embodiment, according to FIG. 9, a first long-gap ejector 10 is
positioned transversely with respect to the running direction T,
while a second long-gap ejector 11 positioned at a distance is
arranged obliquely with respect to the transport direction T. The
order can also be reversed. In the case of the sixth exemplary
embodiment according to FIG. 10, both long-gap ejectors 10, 11 are
arranged obliquely with respect to the transport direction T. The
angle with respect to the transport direction T can be selected on
the basis of the choice of the vacuum profile which can be produced
as a result. In the seventh exemplary embodiment, according to FIG.
11, the long-gap ejectors 10, 11 are arranged one after another in
a row, forming a suction strip 39. As illustrated in FIG. 11, this
suction strip 39 can form a central strip. Alternatively, an edge
strip or edge strips on both sides can be provided. Otherwise, the
above explanations relating to exemplary embodiments one to four
apply in a corresponding way here.
[0045] FIGS. 12a and 12b show an eighth and ninth exemplary
embodiment of the vacuum belt conveying device 1, which differ from
the above embodiments in that the long gap 17, 18 does not have a
cross-sectional narrowing, i.e. has parallel side walls. The
efficiency is lower, so that the long-gap ejector 10, 11 is
preferably arranged closer to the inside of the run 6 of the
transport belt 5. Otherwise, the explanations relating to the first
exemplary embodiment according to FIG. 2 apply in a corresponding
way to the eighth exemplary embodiment according to FIG. 12a. The
explanations relating to the third and fourth exemplary embodiment
according to FIGS. 7 and 8 apply in a corresponding way to the
ninth exemplary embodiment according to FIG. 12b.
[0046] According to a further exemplary embodiment, not
illustrated, the vacuum belt conveying device 1 can also operate
rotated through 180.degree. , that is to say the vacuum is applied
to the return run, with corresponding rotation of the long-gap
ejectors and reversal of the transport direction.
[0047] All publications and patent applications mentioned in this
specification are herein incorporated by reference to the same
extent as if each individual publication or patent application was
specifically and individually indicated to be incorporated by
reference.
[0048] The invention now being fully described, it will be apparent
to one of ordinary skill in the art that many changes and
modifications can be made thereto without departing from the spirit
or scope of the appended claims.
* * * * *